Eternal Sunshine of the Spotless Mind

How happy is the blameless vestal's lot?
The world forgetting, by the world forgot.
Eternal Sunshine of the Spotless Mind.
Each prayer accepted and each wish resigned.

-- Alexander Pope, taken from its eponymn
( Movie: Eternal Sunshine of the Spotless Mind )

I counldn't understand the meaning properly untill i read Eloisa to Abelard http://en.wikipedia.org/wiki/Eloisa_to_Abelard